Day 3 of The Post’s five-day series ranking the playoff teams in specific areas. Previously, we ranked the coaches and receiving corps. Here are the defenses:

1. Giants

Unit gelled into the NFL’s best in the second half of the season and has been practically impenetrable over the past month. They forced 22 turnovers in the final nine games and have allowed 300 yards just once in their past four games.

2. Patriots

They got rid of Chandler Jones and Jamie Collins — two of the league’s best young defensive playmakers — and somehow got better on defense. Finished No. 1 in points allowed for the first time since 2003.

3. Cowboys

A fifth-place finish in scoring defense was especially impressive considering how ravaged by injuries and suspensions Dallas was all season. The injuries haven’t gone away, either, so the playoff bye week should help.

4. Chiefs

They gave up a lot of yards but not many points and were ridiculously opportunistic, finishing with a plus-16 turnover margin. All-Pro safety Eric Berry is the heart of this unit, though, so a heel injury that could keep him out of the divisional round is a big concern.

5. Steelers

The defense was a huge liability during a 4-5 start, but Pittsburgh turned things around after that and allowed 275 yards or fewer in four of the final seven games. They spread the pressure around, too: The Steelers finished with 38 sacks, but no defender had more than five.

6. Texans

With the hapless Brock Osweiler at quarterback most of the season, Romeo Crennel’s defense carried Houston into the playoffs. That feat was even more impressive considering the Texans did it without J.J. Watt. Jadeveon Clowney is finally living up to his billing and the secondary is downright suffocating.

7. Packers

Green Bay’s midseason defensive turnaround was stunning — a unit that allowed 40-plus points in consecutive games during a 4-6 start suddenly transformed into a turnover machine. The Packers had 15 takeaways during the six-game win streak that carried them to the postseason, and good luck running on them.

8. Seahawks

Don’t let the No. 5 finish in yards allowed fool you: This isn’t the same ferocious Seattle defense since safety Earl Thomas was lost for the year in early December. The Seahawks gave up an average of 25 points in their final four games and limp into the playoffs.

9. Lions

Fell apart the final month of the season, especially against the run, and limp into the playoffs on the defensive side of the ball. The Lions are now ridiculously easy to run on, having allowed an average of 144 rushing yards in their final three games.

10. Dolphins

Miami’s once-sturdy defense collapsed the final two weeks of the regular season, giving up 589 yards in a narrow win over the Bills and 396 yards in a blowout loss to the Patriots. The Dolphins have also allowed 100 or more rushing yards in an astounding seven consecutive games.

11. Raiders

Oakland was a defensive sieve all season, but made up for it by forcing turnovers in bunches, resulting in a plus-16 takeaway margin. Khalil Mack might be the NFL’s best defensive player, but the rest of the Raiders’ defense doesn’t inspire much confidence.

12. Falcons

Atlanta’s 11-5 finish was almost entirely one-sided — and that side wasn’t the defense. While the Matt Ryan-led offense was putting up pinball-like numbers, the Falcons defense struggled to stop anyone and finished 25th in yards allowed and 27th in points allowed.